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Articles 2851 - 2880 of 3535

Full-Text Articles in Nanoscience and Nanotechnology

Uncertainty Quantification Models For Micro-Scale Squeeze-Film Damping, Xiaohui Guo, Jia Li, Dongbin Xiu, Alina Alexeenko Apr 2010

Uncertainty Quantification Models For Micro-Scale Squeeze-Film Damping, Xiaohui Guo, Jia Li, Dongbin Xiu, Alina Alexeenko

PRISM: NNSA Center for Prediction of Reliability, Integrity and Survivability of Microsystems

Two squeeze-film gas damping models are proposed to quantify uncertainties associated with the gap size and the ambient pressure. Modeling of gas damping has become a subject of increased interest in recent years due to its importance in micro-electro-mechanical systems (MEMS). In addition to the need for gas damping models for design of MEMS with movable micro-structures, knowledge of parameter dependence in gas damping contributes to the understanding of device-level reliability. In this work, two damping models quantifying the uncertainty in parameters are generated based on rarefied flow simulations. One is a generalized polynomial chaos (gPC) model, which is a …

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Fabrication Of Conductive Interconnects By Ag Migration In Cu-Ag Core-Shell Nanoparticles, Suk Jun Kim, E A. Stach, Carol A. Handwerker Apr 2010

Fabrication Of Conductive Interconnects By Ag Migration In Cu-Ag Core-Shell Nanoparticles, Suk Jun Kim, E A. Stach, Carol A. Handwerker

Birck and NCN Publications

Fabrication of conductive nanoparticle films is observed in Cu-Ag core-shell nanoparticles by fast diffusion of Ag at 220 degrees C from particle surfaces, leading to the formation of sintered necks of Ag at the initial particle-particle contacts. Transmission electron microscopy showed that the necks were pure Ag and that particle surfaces away from the contacts were nearly Ag-free. The extent of neck formation is controllable by the choice of initial Ag thickness. Analysis of the thermodynamics of the Ag-Cu system and the relative diffusivities of Ag and Cu provide criteria for fabrication of other core-shell two-phase systems by the same …

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Optical Limiting Study Of Double Wall Carbon Nanotube-Fullerene Hybrids, Kang-Shyang Liao, Jun Wang, Daniel Fruchtl, Nigel Alley, Enrico Andreoli, Eoghan Dillon, Andrew Barron, Hansoo Kim, Hugh Byrne, Werner Blau, Seamus Curran Apr 2010

Optical Limiting Study Of Double Wall Carbon Nanotube-Fullerene Hybrids, Kang-Shyang Liao, Jun Wang, Daniel Fruchtl, Nigel Alley, Enrico Andreoli, Eoghan Dillon, Andrew Barron, Hansoo Kim, Hugh Byrne, Werner Blau, Seamus Curran

Articles

In order to merge complementary temporal and spatial nonlinear optical characteristics of Fullerene and carbon nanotubes, synthesis of double wall carbon nanotube-Fullerene hybrid was performed by covalently linking DWNT and C60 by amination reaction with polyethylenimine. DWNT-Fullerene hybrids were characterized by thermogravimetric analysis, UV-vis spectroscopy and transmission electron microscopy. Optical limiting performance of DWNT-Fullerene hybrids is superior to those of Fullerenes and SWNTs at the same level (~ 80%) of transmission. Whereas nonlinear scattering is an evident mechanism, reverse saturable absorption from Fullerene moieties has significant contribution. Charge transfer between the DWNT and Fullerene moieties may play an important role …

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Morphological Evolution Of Single-Crystal Ultrathin Solid Films, Mikhail Khenner Mar 2010

Morphological Evolution Of Single-Crystal Ultrathin Solid Films, Mikhail Khenner

Mathematics Faculty Publications

An introduction to mathematical modeling of ultrathin solid films and the role of such modeling in nanotechnologies: Educational presentation for senior physics majors

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Morphological Evolution Of Single-Crystal Ultrathin Solid Films, Mikhail Khenner Mar 2010

Morphological Evolution Of Single-Crystal Ultrathin Solid Films, Mikhail Khenner

Mathematics Faculty Publications

An introduction to mathematical modeling of ultrathin solid films and the role of such modeling in nanotechnologies: Educational/Research presentation for senior physics majors

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Artificial Intelligence: Soon To Be The World’S Greatest Intelligence, Or Just A Wild Dream?, Edward R. Kollett Mar 2010

Artificial Intelligence: Soon To Be The World’S Greatest Intelligence, Or Just A Wild Dream?, Edward R. Kollett

Academic Symposium of Undergraduate Scholarship

The purpose of the paper was to examine the field of artificial intelligence. In particular, the paper focused on what has been accomplished towards the goal of making a machine that can think like a human, and the hardships that researchers in the field has faced. It also touched upon the potential outcomes of success. Why is this paper important? As computers become more powerful, the common conception is that they are becoming more intelligent. As computers become more integrated with society and more connected with each other, people again believe they are becoming smarter. Therefore, it is important that …

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Strain-Induced, Off-Diagonal, Same-Atom Parameters In Empirical Tight-Binding Theory Suitable For [110] Uniaxial Strain Applied To A Silicon Parametrization, Timothy B. Boykin, Mathieu Luisier, Mehdi Salmani-Jelodar, Gerhard Klimeck Mar 2010

Strain-Induced, Off-Diagonal, Same-Atom Parameters In Empirical Tight-Binding Theory Suitable For [110] Uniaxial Strain Applied To A Silicon Parametrization, Timothy B. Boykin, Mathieu Luisier, Mehdi Salmani-Jelodar, Gerhard Klimeck

Birck and NCN Publications

State-of-the-art transistors achieve their improved performance through strain engineering. The somewhat unusual uniaxial [110] strain is of particular importance as it provides a significant mobility increase for electrons. Empirical tight binding has shown tremendous benefits in modeling realistically large structures including standard strain conditions, but often fails to predict the correct uniaxial [110] strain behavior because most treatments neglect the same-atom different-orbital matrix elements induced by this strain. Two separate mechanisms are responsible for these conditions: Loumlwdin orbital changes and displacement of nearest-neighbor potentials. We present a model which separately includes both mechanisms via parameters whose range of validity can …

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Electronic Transport In Chemical Vapor Deposited Graphene Synthesized On Cu: Quantum Hall Effect And Weak Localization, Helin Cao, Qingkai Yu, Luis A. Jauregui, J Tian, W Wu, Z Liu, Ramaneh Jalilian, D K. Benjamin, Z Jiang, J Bao, S S. Pei, Yong P. Chen Mar 2010

Electronic Transport In Chemical Vapor Deposited Graphene Synthesized On Cu: Quantum Hall Effect And Weak Localization, Helin Cao, Qingkai Yu, Luis A. Jauregui, J Tian, W Wu, Z Liu, Ramaneh Jalilian, D K. Benjamin, Z Jiang, J Bao, S S. Pei, Yong P. Chen

Birck and NCN Publications

We report on electronic properties of graphene synthesized by chemical vapor deposition (CVD) on copper then transferred to SiO2/Si. Wafer-scale (up to 4 in.) graphene films have been synthesized, consisting dominantly of monolayer graphene as indicated by spectroscopic Raman mapping. Low temperature transport measurements are performed on microdevices fabricated from such CVD graphene, displaying ambipolar field effect (with on/off ratio similar to 5 and carrier mobilities up to similar to 3000 cm(2)/V s) and "half-integer" quantum Hall effect, a hall-mark of intrinsic electronic properties of monolayer graphene. We also observe weak localization and extract information about phase coherence and scattering …

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Note: Thermal Analog To Atomic Force Microscopy Force-Displacement Measurements For Nanoscale Interfacial Contact Resistance, Brian D. Iverson, John Blendell, Suresh Garimella Mar 2010

Note: Thermal Analog To Atomic Force Microscopy Force-Displacement Measurements For Nanoscale Interfacial Contact Resistance, Brian D. Iverson, John Blendell, Suresh Garimella

Birck and NCN Publications

Thermal diffusion measurements on polymethylmethacrylate-coated Si substrates using heated atomic force microscopy tips were performed to determine the contact resistance between an organic thin film and Si. The measurement methodology presented demonstrates how the thermal contrast signal obtained during a force-displacement ramp is used to quantify the resistance to heat transfer through an internal interface. The results also delineate the interrogation thickness beyond which thermal diffusion in the organic thin film is not affected appreciably by the underlying substrate.

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A Continuum Plasticity Model That Accounts For Hardening And Size Effects In Thin Films, Abigail Hunter, Hariharanath Kavuri, Marisol Koslowski Mar 2010

A Continuum Plasticity Model That Accounts For Hardening And Size Effects In Thin Films, Abigail Hunter, Hariharanath Kavuri, Marisol Koslowski

PRISM: NNSA Center for Prediction of Reliability, Integrity and Survivability of Microsystems

We conducted three-dimensional finite element simulations of the mechanical response of passivated single crystal copper thin films with a continuum crystal plasticity model. The model introduces the formation of high density dislocation layers close to the substrate and passivation interfaces obtained from dislocation dynamics simulations. These dislocation structures are responsible for an increase in strain hardening as the film thickness decreases. The model predicts an increase in strain hardening as the film thickness decreases in agreement with experimental observation in films with thickness in the range 0.2 to 2μm.

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Pced2.0—A Computer Program For The Simulation Of Polycrystalline Electron Diffraction Pattern, Xingzhong Li Mar 2010

Pced2.0—A Computer Program For The Simulation Of Polycrystalline Electron Diffraction Pattern, Xingzhong Li

Nebraska Center for Materials and Nanoscience: Faculty Publications

A computer program for the simulation of polycrystalline electron diffraction patterns is described. PCED2.0, an upgraded version of the previous JECP/PCED, can be used as a teaching aid and research tool for phase identification, microstructure texture analysis, and phase fraction determination. In addition to kinematical theory for diffraction intensity calculation of polycrystalline samples, Blackman two-beam dynamical correction is included. March model is used for out-of-plane and in-plane texture simulation. A pseudo-Voigt function is used for the peak profile fitting of diffraction rings. User-friendly interface is improved in the handling of experimental diffraction data and the flexibility of indexing. Application of …

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Automated Nanocrystal Orientation And Phase Mapping In The Transmission Electron Microscope On The Basis Of Precession Electron Diffraction, Edgar F. Rauch, Joaquin Portillo, Stavros Nicolopoulos, Daniel Bultreys, Sergei Rouvimov, Peter Moeck Mar 2010

Automated Nanocrystal Orientation And Phase Mapping In The Transmission Electron Microscope On The Basis Of Precession Electron Diffraction, Edgar F. Rauch, Joaquin Portillo, Stavros Nicolopoulos, Daniel Bultreys, Sergei Rouvimov, Peter Moeck

Physics Faculty Publications and Presentations

An automated technique for the mapping of nanocrystal phases and orientations in a transmission electron microscope is described. It is primarily based on the projected reciprocal lattice geometry that is extracted from electron diffraction spot patterns. Precession electron diffraction patterns are especially useful for this purpose. The required hardware allows for a scanning-precession movement of the primary electron beam on the crystalline sample and can be interfaced to any older or newer mid-voltage transmission electron microscope (TEM). Experimentally obtained crystal phase and orientation maps are shown for a variety of samples. Comprehensive commercial and open-access crystallographic databases may be used …

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On Momentum Conservation And Thermionic Emission Cooling, Raseong Kim, Changwook Jeong, Mark S. Lundstrom Mar 2010

On Momentum Conservation And Thermionic Emission Cooling, Raseong Kim, Changwook Jeong, Mark S. Lundstrom

Birck and NCN Publications

The possibility of increasing the performance of thermionic cooling devices by relaxing lateral momentum conservation is examined. Upper limits for the ballistic emission current are established. It is then shown that for most cases, nonconserved lateral momentum model produces a current that exceeds this upper limit. For the case of heterojunctions with a much heavier effective mass in the barrier and with a low barrier height, however, relaxing lateral momentum may increase the current. These results can be simply understood from the general principle that the current is limited by the location, well or barrier, with the smallest number of …

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Communications: Entanglement Switch For Dipole Arrays, Qi Wei, Sabre Kais, Yong P. Chen Mar 2010

Communications: Entanglement Switch For Dipole Arrays, Qi Wei, Sabre Kais, Yong P. Chen

Birck and NCN Publications

We propose a new entanglement switch of qubits consisting of electric dipoles oriented along or against an external electric field and coupled by the electric dipole-dipole interaction. The pairwise entanglement can be tuned and controlled by the ratio of the Rabi frequency and the dipole-dipole coupling strength. Tuning the entanglement can be achieved for one, two, and three-dimensional arrangements of the qubits. The feasibility of building such an entanglement switch is also discussed.

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Microscopic And Spectroscopic Studies Of Thermally Enhanced Electrospun Pmma Micro- And Nanofibers, Sean Pelfrey, Travis Cantu, Michael R. Papantonakis, Duane L. Simonson, R. Andrew Mcgill, Javier Macossay-Torres Mar 2010

Microscopic And Spectroscopic Studies Of Thermally Enhanced Electrospun Pmma Micro- And Nanofibers, Sean Pelfrey, Travis Cantu, Michael R. Papantonakis, Duane L. Simonson, R. Andrew Mcgill, Javier Macossay-Torres

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

Carbon nanofibers (CNFs) have been incorporated into poly(methyl methacrylate) (PMMA) through electrospinning. The resulting micro- and nanofibers have been characterized by Scanning Electron Microscopy (SEM), which confirmed fiber formation and demonstrated a core-sheath structure of the PMMA fibers. Thermogravimetric Analysis (TGA) was used to obtain the thermal properties of the materials, indicating an enhancement in the thermal properties of the composite fibers. In addition, Fourier Transform Infrared Spectroscopy (FTIR) was utilized to investigate the interactions of PMMA micro- and nanofibers with CNFs, demonstrating the preferred sites of intermolecular interactions between the polymer matrix and the filler.

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Preparation And Electrochemical Behavior Of Li4Ti5O12 Nanosheets As Anode Material For Lithium Ion Battery, Yi-Fei Wang, Yu-Feng Tang, Zheng Qiu, Li Yang Feb 2010

Preparation And Electrochemical Behavior Of Li4Ti5O12 Nanosheets As Anode Material For Lithium Ion Battery, Yi-Fei Wang, Yu-Feng Tang, Zheng Qiu, Li Yang

Journal of Electrochemistry

Spinel lithium titanate(Li4Ti5O12) nanosheets with a size range of 200 ～400 nm were synthesized by hydrothermal process from the amorphous hydrous titanium oxide precursors.The as-prepared products were characterized by X-ray powder diffraction(XRD),scanning electron microscopy(SEM) and transmission electron microscopy(TEM).The electrochemical behaviors of Li4Ti5O12 electrode in conventional organic electrolyte and ionic liquid electrolyte were investigated by using cyclic voltammetry,galvanostatic charge-discharge and AC impedance techniques.The experimental results indicate that the as-prepared nanostructured Li4Ti5O12,evaluated as anode material,exhibited good reversibility and cycle performance.It is expected to be a …

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Electrocatalytic Reduction Of L-Cystine At Pb/Nanotio2 Film Electrode, Dao-Bao Chu, Feng Wang, Ying Xiao, Xue-Jiao Zhang Feb 2010

Electrocatalytic Reduction Of L-Cystine At Pb/Nanotio2 Film Electrode, Dao-Bao Chu, Feng Wang, Ying Xiao, Xue-Jiao Zhang

Journal of Electrochemistry

The nanoporous Ti-based TiO2 films electrodes modified with Pb particles(Pb/nanoTiO2) were prepared by using anodization and potentiostatic electro-deposition.The optimum deposition conditions were determined by comparing with various deposition potentials and time.The SEM analyses indicated that the TiO2 films were homogeneous nanoporous structure,and the Pb particles well dispersed on the TiO2 films.The L-cystine electrocatalytic activity reduction on the Pb/nanoTiO2 film electrodes was investigated by cyclic voltammetry and Chronoamperometric curves.The results showed that this type of the electrode posseses high acticity and stability.

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Electronic Structure, Phonons, And Thermal Properties Of Scn, Zrn, And Hfn: A First-Principles Study, Bivas Saha, Jagaran Acharya, Timothy D. Sands, Umesh Waghmare Feb 2010

Electronic Structure, Phonons, And Thermal Properties Of Scn, Zrn, And Hfn: A First-Principles Study, Bivas Saha, Jagaran Acharya, Timothy D. Sands, Umesh Waghmare

Birck and NCN Publications

With a motivation to understand microscopic aspects of ScN, ZrN, and HfN relevant to the thermoelectric properties of nitride metal/semiconductor superlattices, we determine their electronic structure, vibrational spectra and thermal properties using first-principles calculations based on density functional theory with a generalized gradient approximation of the exchange correlation energy. We find a large energy gap in the phonon dispersions of metallic ZrN and HfN, but a gapless phonon spectrum for ScN spanning the same energy range, this suggests that a reduced thermal conductivity, suitable for thermoelectric applications, should arise in superlattices made with ScN and ZrN or ScN and HfN. …

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On Eigenmodes, Stiffness, And Sensitivity Of Atomic Force Microscope Cantilevers In Air Versus Liquids, Daniel Kiracofe, Arvind Raman Feb 2010

On Eigenmodes, Stiffness, And Sensitivity Of Atomic Force Microscope Cantilevers In Air Versus Liquids, Daniel Kiracofe, Arvind Raman

Birck and NCN Publications

The effect of hydrodynamic loading on the eigenmode shapes, modal stiffnesses, and optical lever sensitivities of atomic force microscope (AFM) microcantilevers is investigated by measuring the vibrations of such microcantilevers in air and water using a scanning laser Doppler vibrometer. It is found that for rectangular tipless microcantilevers, the measured fundamental and higher eigenmodes and their equivalent stiffnesses are nearly identical in air and in water. However, for microcantilevers with a tip mass or for picket shaped cantilevers, there is a marked difference in the second (and higher) eigenmode shapes between air and water that leads to a large decrease …

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Complex Martensitic Nanostructure In Zr Nanowires: A Molecular Dynamics Study, Alexander Thompson, Alejandro Strachan Feb 2010

Complex Martensitic Nanostructure In Zr Nanowires: A Molecular Dynamics Study, Alexander Thompson, Alejandro Strachan

Birck and NCN Publications

We use molecular dynamics to characterize the martensitic nanostructure that develops when bcc Zr nanowires are cooled down and transform to hcp (martensite). We find that size has a strong effect on nanostructure and even very small wires (a few nanometers in diameter) exhibit complex, multidomain structures with large internal strains (up to similar to 6%). Long and thin wires result in domains coexisting along their axes while those with small aspect ratios exhibit coexistence of domains within their cross-section. We also that find regions of fcc Zr that develop to bridge neighboring hcp domains.

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Scanning Tunneling Microscope Study Of Striated Carbon Ridges In Few-Layer Epitaxial Graphene Formed On 4h-Silicon Carbide (0001), Sara E. Harrison, Michael A. Capano, R. Reifenberger Feb 2010

Scanning Tunneling Microscope Study Of Striated Carbon Ridges In Few-Layer Epitaxial Graphene Formed On 4h-Silicon Carbide (0001), Sara E. Harrison, Michael A. Capano, R. Reifenberger

Birck and NCN Publications

Atomically resolved scanning tunneling microscope images of carbon ridge defects found in few-layer graphene formed on the C-face (0001) of 4H-silicon carbide reveal a striated exterior surface formed from out-of-plane distortions of the hexagonal graphene lattice. While ridge formation is likely explained by compressive in-plane stresses coupled with the small values of the bending modulus for few-layer graphene, the striated structure along the ridges argues for a localized unidirectional stress in the material directed along the ridge length.

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Charge-Pumping Characterization Of Interface Traps In Al2o3/In0.75ga0.25as Metal-Oxide-Semiconductor Field-Effect Transistors, W Wang, J. Deng, Jc M. Hwang, Y Xuan, P. D. Ye Feb 2010

Charge-Pumping Characterization Of Interface Traps In Al2o3/In0.75ga0.25as Metal-Oxide-Semiconductor Field-Effect Transistors, W Wang, J. Deng, Jc M. Hwang, Y Xuan, P. D. Ye

Birck and NCN Publications

Charge pumping was used to characterize the interface traps between Al2O3 and In0.75Ga0.25As in an n-channel inversion-mode metal-oxide-semiconductor field-effect transistor (MOSFET). By analyzing the charge pumped under gate voltage pulses of different rise and fall times, the interface trap density was extracted across the band gap of In0.75Ga0.25As. The interface trap density was found to be 4x10(12) cm(-2) eV(-1) near the conduction band and to peak at 3x10(13) cm(-2) eV(-1) mid-gap. The result helps explain the promising on-state performance of the Al2O3/In0.75Ga0.25As MOSFET and the need to further improve the interface so that its off-state performance can be on par …

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Exact Calculation Of Entanglement In A 19-Site Two-Dimensional Spin System, Qing Xu, Sabre Kais, Maxim Naumov, Ahmed Sameh Feb 2010

Exact Calculation Of Entanglement In A 19-Site Two-Dimensional Spin System, Qing Xu, Sabre Kais, Maxim Naumov, Ahmed Sameh

Birck and NCN Publications

Using the trace minimization algorithm, we carried out an exact calculation of entanglement in a 19-site two-dimensional transverse Ising model. This model consists of a set of localized spin-1/2 particles in a two-dimensional triangular lattice coupled through exchange interaction J and subject to an external magnetic field of strength h. We demonstrate, for such a class of two-dimensional magnetic systems, that entanglement can be controlled and tuned by varying the parameter lambda = h/J in the Hamiltonian and by introducing impurities into the systems. Examining the derivative of the concurrence as a function of lambda shows that the system exhibits …

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Band Offsets Of Al2o3/Inxga1-Xas (X=0.53 And 0.75) And The Effects Of Postdeposition Annealing, N V. Nguyen, M Xu, O A. Kirillov, P. D. Ye, C Wang, K Cheung, J S. Suehle Feb 2010

Band Offsets Of Al2o3/Inxga1-Xas (X=0.53 And 0.75) And The Effects Of Postdeposition Annealing, N V. Nguyen, M Xu, O A. Kirillov, P. D. Ye, C Wang, K Cheung, J S. Suehle

Birck and NCN Publications

Band offsets at the interfaces of InxGa1-xAs/Al2O3/Al where x=0.53 and 0.75 were determined by internal photoemission and spectroscopic ellipsometry. The photoemission energy threshold at the InxGa1-xAs/Al2O3 interface was found to be insensitive to the indium composition but shifted to a lower energy after a postdeposition annealing at high temperatures. Subthreshold electron photoemission was also observed for the annealed sample and was attributed to interfacial layer formation during the annealing process.

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Large-Scale Graphitic Thin Films Synthesized On Ni And Transferred To Insulators: Structural And Electronic Properties, Helin Cao, Qingkai Yu, Robert Colby, Deepak Pandey, C S. Park, Jie Lian, Dmitry Zemlyanov, Isaac Childres, V. P. Drachev, E A. Stach, Muhammad Hussain, Hao Li, Steven S. Pei, Yong P. Chen Feb 2010

Large-Scale Graphitic Thin Films Synthesized On Ni And Transferred To Insulators: Structural And Electronic Properties, Helin Cao, Qingkai Yu, Robert Colby, Deepak Pandey, C S. Park, Jie Lian, Dmitry Zemlyanov, Isaac Childres, V. P. Drachev, E A. Stach, Muhammad Hussain, Hao Li, Steven S. Pei, Yong P. Chen

Birck and NCN Publications

We present a comprehensive study of the structural and electronic properties of ultrathin films containing graphene layers synthesized by chemical vapor deposition based surface segregation on polycrystalline Ni foils then transferred onto insulating SiO2/Si substrates. Films of size up to several mm's have been synthesized. Structural characterizations by atomic force microscopy, scanning tunneling microscopy, cross-sectional transmission electron microscopy (XTEM), and Raman spectroscopy confirm that such large-scale graphitic thin films (GTF) contain both thick graphite regions and thin regions of few-layer graphene. The films also contain many wrinkles, with sharply-bent tips and dislocations revealed by XTEM, yielding insights on the growth …

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Fourier Transform Infrared Microspectroscopy And Multivariate Methods For Radiobiological Dosimetry, Aidan Meade, Colin Clarke, Hugh Byrne, Fiona Lyng Feb 2010

Fourier Transform Infrared Microspectroscopy And Multivariate Methods For Radiobiological Dosimetry, Aidan Meade, Colin Clarke, Hugh Byrne, Fiona Lyng

Articles

The scientific literature contains an ever-growing number of reports of applications of vibrational spectroscopy as a multivariate non-invasive tool for analysis of biological effects at the molecular level. Recently, Fourier transform infrared microspectroscopy (FTIRM) has been demonstrated to be sensitive to molecular events occurring in cells and tissue after exposure to ionizing radiation. In this work the application of FTIRM in the examination of dose-dependent molecular effects occurring in skin cells after exposure to ionizing radiation with the use of partial least-squares regression (PLSR) and generalized regression neural networks (GRNN) was studied. The methodology is shown to be sensitive to …

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Bdf-Like Methods For Nonlinear Dynamic Analysis, S. Dong Jan 2010

Bdf-Like Methods For Nonlinear Dynamic Analysis, S. Dong

PRISM: NNSA Center for Prediction of Reliability, Integrity and Survivability of Microsystems

We present several time integration algorithms of second-order accuracy that are numerically simple and effective for nonlinear elastodynamic problems. These algorithms are based on a general four-step scheme that has a resemblance to the backward differentiation formulas. We also present an extension to the composite strategy of the Bathe method. Appropriate values for the algorithmic parameters are determined based on considerations of stability and dissipativity, and less dissipative members of each algorithm have been identified. We demonstrate the convergence characteristics of the proposed algorithms with a nonlinear dynamic problem having analytic solutions, and test these algorithms with several three-dimensional nonlinear …

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Oscillatory And Monotonic Modes Of Long-Wave Marangoni Convection In A Thin Film, Sergey Shklyaev, Mikhail Khenner, Alexei Alabuzhev Jan 2010

Oscillatory And Monotonic Modes Of Long-Wave Marangoni Convection In A Thin Film, Sergey Shklyaev, Mikhail Khenner, Alexei Alabuzhev

Mathematics Faculty Publications

We study long-wave Marangoni convection in a layer heated from below. Using the scaling k=O Bi, where k is the wave number and Bi is the Biot number, we derive a set of amplitude equations. Analysis of this set shows presence of monotonic and oscillatory modes of instability. Oscillatory mode has not been previously found for such direction of heating. Studies of weakly nonlinear dynamics demonstrate that stable steady and oscillatory patterns can be found near the stability threshold.

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Oscillatory And Monotonic Modes Of Long-Wave Marangoni Convection In A Thin Film, Sergey Shklyaev, Mikhail Khenner, Alexei Alabuzhev Jan 2010

Oscillatory And Monotonic Modes Of Long-Wave Marangoni Convection In A Thin Film, Sergey Shklyaev, Mikhail Khenner, Alexei Alabuzhev

Mathematics Faculty Publications

We study long-wave Marangoni convection in a layer heated from below. Using the scaling k=O Bi, where k is the wave number and Bi is the Biot number, we derive a set of amplitude equations. Analysis of this set shows presence of monotonic and oscillatory modes of instability. Oscillatory mode has not been previously found for such direction of heating. Studies of weakly nonlinear dynamics demonstrate that stable steady and oscillatory patterns can be found near the stability threshold.

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Luminescence Enhancement Of Cdte Nanostructures In Laf3:Ce/Cdte Nanocomposites, Mingzhen Yao, Xing Zhang, Lun Ma, Wei Chen, Alan G. Joly, Jinsong Huang, Qingwu Wang Jan 2010

Luminescence Enhancement Of Cdte Nanostructures In Laf3:Ce/Cdte Nanocomposites, Mingzhen Yao, Xing Zhang, Lun Ma, Wei Chen, Alan G. Joly, Jinsong Huang, Qingwu Wang

Department of Mechanical and Materials Engineering: Faculty Publications

Radiation detection demands new scintillators with high quantum efficiency, high energy resolution, and short luminescence lifetimes. Nanocomposites consisting of quantum dots and Ce3+ doped nanophosphors may be able to meet these requirements. Here, we report the luminescence enhancement of LaF3:Ce/CdTe nanocomposites which were synthesized by a wet chemistry method. CdTe quantum dots in LaF3:Ce/CdTe nanocomposites are converted into nanowires, while in LaF3 /CdTe nanocomposites no such conversion is observed. As a result, the CdTe luminescence in LaF3:Ce/CdTe nanocomposites is enhanced about five times, while in LaF3 /CdTe nanocomposites no enhancement was …

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